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Surface spectroscopic study of the behaviour of a thin TiN layer as protective coating of iron against corrosion by humid SO 2 ‐aggressive environments
Author(s) -
Marco J. F.,
Agudelo A. C.,
Gancedo J. R.,
Hanžel Darko
Publication year - 1998
Publication title -
surface and interface analysis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.52
H-Index - 90
eISSN - 1096-9918
pISSN - 0142-2421
DOI - 10.1002/(sici)1096-9918(199808)26:9<667::aid-sia413>3.0.co;2-0
Subject(s) - relative humidity , tin , x ray photoelectron spectroscopy , coating , corrosion , atmosphere (unit) , layer (electronics) , auger electron spectroscopy , scanning electron microscope , chemistry , metallurgy , humidity , materials science , analytical chemistry (journal) , chemical engineering , environmental chemistry , composite material , meteorology , physics , nuclear physics , engineering
In this work the behaviour of thin (30 nm), single‐layer TiN coatings on iron in different humid SO 2 ‐aggressive environments [(i) [SO 2 ]=0.001% v/v, 80% relative humidity; (ii) [SO 2 ]=0.001% v/v, 98% relative humidity; (iii) [SO 2 ]=0.04% v/v, 80% relative humidity; (iv) [SO 2 ]=0.04% v/v, 98% relative humidity] has been studied by integral conversion electron Mössbauer spectroscopy (ICEMS), XPS, AES and scanning auger microscopy (SAM). The results show that in atmosphere (i) there is no degradation of either the TiN coating or the underlying iron even after 14 days of exposure, whilst in atmosphere (iv) the TiN coating is completely destroyed after 7 days of exposure. In other cases the XPS data show that there are no significant chemical changes in the TiN coatings with exposure time; however, the ICEMS data show that after a sufficiently long exposure period, whose duration depends on the characteristics of the SO 2 atmosphere, the underlying iron corrodes to give Fe 2+ and Fe 3+ species. This is attributed to the existence of small pores in the TiN coating, which allow the permeation of SO 2 , O 2 and H 2 O from the atmosphere to the TiN/Fe interface. © 1998 John Wiley & Sons, Ltd.